1. Field of the Invention
The present invention relates to an inertial drive actuator.
2. Description of the Related Art
As a conventional example of an actuator in which, a movement of an object is made possible by a driving mechanism in which, an electromechanical transducer is used, a mobile table 200 described in Japanese Patent Application Laid-open Publication No. Hei 8-340682 is available. The mobile table 200 will be described below by referring to FIG. 11. FIG. 11 is an exploded perspective view showing a structure of a conventional actuator.
The mobile table 200 includes an actuator 210 in X-axis direction and an actuator 220 in Y-axis direction. The actuator 210 in X-axis direction includes supporting blocks 213 and 214 which are slidably fitted without any slackness on members 201a and 201b respectively of a frame 201, a piezoelectric element 215, a drive shaft 216, a slider block 212, a pad 218, and a plate spring 219. The drive shaft 216 is supported to move freely in an axial direction by a bearing 213a and the supporting block 213 which are formed integrally with the supporting block 214. Moreover, one end of the piezoelectric element 215 is fixed by adhering to the supporting block 213, and the other end thereof is fixed by adhering to one end of the drive shaft 216. The drive shaft 216 is displaceable in X-axis direction by a displacement of the piezoelectric element 215 in a direction of thickness.
Moreover, the actuator 220 in Y-axis direction includes supporting blocks 223 and 224 which are slidably fitted without any slackness on members 201c and 201d respectively of the frame 201, a piezoelectric element 225, a drive shaft 226, the slider block 212, a pad 228, and a plate spring 229. The drive shaft 226 is supported to move freely in an axial direction by a bearing 223a and the supporting block 224 which are formed integrally with the supporting block 223. Moreover, one end of the piezoelectric element 225 is fixed by adhering to the supporting block 223, and the other end thereof is fixed by adhering to one end of the drive shaft 226. The drive shaft 226 is displaceable in Y-axis direction by a displacement of the piezoelectric element 225 in a direction of thickness. In the abovementioned structure, by driving the piezoelectric element 215 or the piezoelectric element 225, the slider block 212 is displaced via the drive shaft 216 or the drive shaft 226, and accordingly, a table T disposed on the slider block 212 is moved in X-axis direction and Y-axis direction.
However, in the mobile table 200 in FIG. 11, since the slider block 212 does not move except in a direction of elongation and contraction of the piezoelectric elements 215 and 225, for moving in an arbitrary direction in XY plane, the structure has to be made complicated. Moreover, for moving in a desired trajectory, a sophisticated (a high degree) position detecting mechanism is necessary, and lowering the cost has been difficult.